Friday 14 September 2012 18.50 EDT
First published on Friday 14 September 2012 18.50 EDT

Police are investigating after a chemistry student at the University of Southampton was poisoned with highly toxic substances. The 25-year-old PhD student was taken to hospital after falling ill three weeks ago. Tests revealed he had thallium and arsenic in his body.

It is not known how the student was exposed to the chemicals but as a precaution the university has closed some of its chemistry labs while investigations continue. It is not believed there is a risk to public health.

Police said they are working closely with the university, the Health Protection Agency and the Health and Safety Executive to find out what happened to the unnamed student, who is being treated at a toxicology unit at a hospital in Cardiff. His condition is not known.

Hampshire fire and rescue service's specialist unit is conducting tests at a property in Southampton.

"This is being treated as an isolated incident and staff and students at the university and other members of the public are not believed to be at risk," a Hampshire police spokesman said.

Detective Chief Inspector Pete McGowan said: "We are keeping an open mind on how the student has been exposed to the chemicals and are investigating all scenarios at the moment. We and the HSE are leading this inquiry and we have no reason to think that there is any risk to public health."

University provost and deputy vice-chancellor Adam Wheeler said: "Our thoughts are with our student and their family at this difficult time for them.

"The university's student support staff are providing them with further assistance.

"The safety of our staff and students is of paramount importance to the university and we have taken measures to ensure their health and wellbeing.

"As part of this we are co-operating with and taking advice from the relevant authorities."

Thallium is a highly toxic odourless and tasteless bluish-white metal that is found in trace amounts in the Earth's crust and is used in the manufacturing of electronic devices.

Exposure to large amounts of the metal will cause vomiting, diarrhoea, temporary hair loss, and will affect the nervous system, lungs, heart, liver, and kidneys and could cause death.

Arsenic is also a highly toxic metalloid and in the past has been used by murderers because the symptoms of arsenic poisoning were not easily distinguishable from other medical conditions.

It also causes multiple organ failure in those who ingest it.

The incident does not relate to any leak or airborne emission from university buildings and is not transmittable and may not be connected with the university at all, police added.